<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
    //  console.log(Boolean(123));
    //  console.log(Boolean(null));
    //  console.log(Boolean(NaN)); 
    //  if(123){
    //      console.log("nb");
    //  };
    //  if(NaN){
    //     console.log("nb");
    //  };
    // var arsd4='xiao liu';
    // console.log(btoa(arsd4));
    // console.log(atob('eGlhbyBsaXU='));


    // 加密
     console.log(arsd4);
     console.log( arsd4[0]);
     console.log( arsd4[1]);
     console.log( arsd4[2]);
     console.log( arsd4[3]);
     console.log(arsd4['length']);


    </script>
</body>
</html>